The title piece in this smoothly written collection, the first from the bestselling mystery novelist, is a novella. Judith Chase is an American historian working in London and enjoying the courtship of Sir Stephen Hallett, due to become England's next prime minister. Beset by vague fears. Judith consults Dr. Patel, famous for treating Anna Anderson, who claimed she was Anastasia of the Russian royal family. ``Retrogressed'' by Patel, Judith finds herself in the 17th century, during the English Civil War and Restoration, (of the monarchy), reliving horrors that the author exploits in full measure. This and the four other stories, (three of them previously published in Woman's Day magazine,) amply demonstrate Clark's skill at maintaining suspense by creating nightmarish situations that lie just beneath the surface of ordinary life. Literary Guild alternate. (Nov.)